Applying trace element geochemistry of archaeological bone to study the coevolution of environmental change and human health in the Roman Empire

Technological change has affected human health dating back to at least the Neolithic agricultural revolution. Growing evidence indicates widespread environmental pollution began with metallurgical practices and continues today. Environmental exposures to trace elements released from these practices have the potential to alter human body composition, such as bone mineral chemistry, especially for elements that are not homeostatically regulated. These signals can be used for inferences about human health, particularly when metallotoxins are detected in abundance. Therefore, trace element geochemistry of archaeological bone may provide a means to evaluate human health through time. However, diagenetic factors can hinder attempts to extract this information. Thus, we employed advanced analytical and interpretive methods to carefully distinct groups of European burials over about 1000 years to address questions of potentially toxic trace element exposures. Here, to address our hypothesis that Roman urbanization created one of the earliest urban toxic environment caused by multiple exposures, we present a comprehensive suite of bone trace element compositions of femora from burials spanning three distinct archaeological time periods (Bronze Age, Iron Age, and Roman period). All bone specimens were obtained from the anterior-mid shaft of carefully selected femora and processed using the same analytical techniques designed to mitigate soil contamination. Our data indicate that widespread environmental pollution accelerated in Londinium during the Roman Empire period, leading to conditions where population health would be vulnerable to environmental changes. Specifically, bone lead, silver, vanadium, arsenic, and cadmium concentrations were typically elevated and would likely be associated with multiple toxicities. In addition, bone iron levels were extremely high in some Londinium burials. Our interpretation is that the Romans inhabiting Londinium were not just poisoned by lead exposure as several previous studies show but by several metallotoxins.